Thank you both for your replies. However, the problem is now fixed. I took one of the old bearings down to the LHS and when the 'mechanic' looked at it, his first reaction was that the bearing is full of oily dirt. What I did about a month ago was put a drop of 3 in 1 oil into each bearing...big mistake. When dirt got into the bearing it couldn't fall out again because it adhered to the oil and eventually 'chewed' the insides to bits. Okay, that's being a little melodramatic, but it did ruin them. So, to make a long story short, he graciously sold me a new set of bearings, I installed them and now the Old Bird is singing happily again!! Not me, the helicopter Again, thank-you for the replies, it was much appreicated!!!